Spin up a background agent to do the research, so you keep working while it reads.

Its job:

Investigate the question against primary sources (official docs, source code, specs, first-party APIs), not a secondary write-up of them. Follow every claim back to the source that owns it.
Write the findings to a single Markdown file, citing each claim's source.
Save it where the repo already keeps such notes; match the existing convention, and if there is none, put it somewhere sensible and say where.

Cross-Client Portability

This skill is written to stay usable across GitHub Copilot, Claude Code, and Codex.

GitHub Copilot: keep the folder in a Copilot-visible skill path or wrap the workflow in project instructions when folder discovery is unavailable.
Claude Code: keep the folder in a local skills directory or a compatible plugin source.
Codex: install or sync the folder into $CODEX_HOME/skills/research and restart Codex after major changes.